/*
 *  Copyright 2011 
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package com.sholink.wheel.adapters;

import java.util.LinkedList;
import java.util.List;

import android.database.DataSetObserver;
import android.view.View;
import android.view.ViewGroup;

/**
 * Abstract Wheel adapter.
 */
public abstract class AbstractWheelAdapter implements WheelViewAdapter {
	// Observers
	private List<DataSetObserver> datasetObservers;

	@Override
	public View getEmptyItem(View convertView, ViewGroup parent) {
		return null;
	}

	@Override
	public void registerDataSetObserver(DataSetObserver observer) {
		if (datasetObservers == null) {
			datasetObservers = new LinkedList<DataSetObserver>();
		}
		datasetObservers.add(observer);
	}

	@Override
	public void unregisterDataSetObserver(DataSetObserver observer) {
		if (datasetObservers != null) {
			datasetObservers.remove(observer);
		}
	}

	/**
	 * Notifies observers about data changing
	 */
	public void notifyDataChangedEvent() {
		if (datasetObservers != null) {
			for (DataSetObserver observer : datasetObservers) {
				observer.onChanged();
			}
		}
	}

	/**
	 * Notifies observers about invalidating data
	 */
	public void notifyDataInvalidatedEvent() {
		if (datasetObservers != null) {
			for (DataSetObserver observer : datasetObservers) {
				observer.onInvalidated();
			}
		}
	}
}
